For those living in the stone age -- or not living in the stoner age -- 420 (pronounced "four-twenty," dude) refers to the universally accepted stoner national holiday, when all things pot are celebrated. The term was first used by a group of Deadheads in San Rafael, Calfornia, in 1971, who used 4:20 p.m. as their designated meeting time where various nefarious activities may take place. It evolved into a codeword to mean pot smoking in general.

The marijuana subculture will be in force this Friday, April 20, or 4/20 -- and particularly at 4:20 pm. And a lot of them will be lining up to see Marley, the two-and-a-half hour Bob Marley documentary about the famed Rastafarian singer and marijuana smoker who died in 1981 at the age of 36. Macdonald, who also directed The Last King of Scotland and the Oscar-winning doc One Day in September, calls Bob Marley "one of the most creative figures of the 20th Century. He's known by more people around the world than Elvis, Michael Jackson, or The Beatles. In India, in Africa, they all know Bob Marley -- his face is still everywhere."

It wasn't easy to get the film made: Martin Scorsese and Jonathan Demme both tried and failed. But when billionaire Steve Bing gave the greenlight to Macdonald via Marley mentor Chris Blackwell, it fell into place. "I had wanted to make this film eight years ago," says Macdonald. "We researched for a year, it was hard to collect all this material. Then we made it very quickly."

As for distributor Magnolia's decision to release Marley on 4/20, Macdonald says, "I’m sure it’s intentional but it’s got nothing to do with me. Bob is the patron saint of pop smokers, but that’s just a small part of who he is. If that’s a way of attracting people to the film, so be it. It’s not all he is. This was the time [of year] Magnolia wanted to bring the film out anyway. So it seemed to Magnolia that this release date was a no-brainer."